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  /*var a="153496216325";
  console.log(a.indexOf("3"));
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var str="will never change until death";
var words=str.split(" ");
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var str="我终将落俗，但浪漫不死";
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var str1="张上课公然好好学习";
var str2="打游戏";
console.log(str1.replace("好好学习",str2));


var str1="我们会深情拥抱";
var str2="我们会一直到老";
console.log(str1.concat(str2));*/


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